This invention relates to an apparatus and method for injection molding, for example for encapsulating integrated circuits.
Injection molding apparatus, such as a transfer molding installation for encapsulating integrated circuits, typically involves a plurality of molding presses associated with a plurality of movable robots for loading and unloading the molding presses. For example, a row of molding presses may be arranged with a loading robot and unloading robot movable along the row to insert integrated circuit leadframes into the molds and remove the encapsulated integrated circuits after molding. However, several difficulties are associated with this type of arrangement, one of those being potential interference between the loading and unloading robots, for example, in accessing one of the plurality of molding presses.
Accordingly, the present invention provides an injection molding apparatus comprising a plurality of molding presses each adapted to receive at least one mold, each mold defining a cavity shaped for the formation of a molded product, the plurality of molding presses being mounted for rotational movement about a common axis with respect to a plurality of stations arranged around the plurality of molding presses, the molding apparatus being adapted to sequentially align ones of said plurality of molding presses with one of said stations for loading of molding material and unloading of a molded product
The present invention also provides an integrated circuit encapsulation apparatus comprising a plurality of transfer molding presses mounted on a rotatable index table, each molding press being adapted to receive at least one mold defining a cavity adapted to receive an integrated circuit die and attached leadframe for encapsulation thereof, and a plurality of stations arranged around the rotatable index table wherein indexed rotation of the table is effective to align ones of the molding presses with one of the stations, said stations including an insert loading station for loading an integrated circuit die and attached leadframe into a mold of a mold press aligned therewith, a molding compound loading station for loading an encapsulation material into a pot of an aligned molding press, and an unloading station for removing an encapsulated integrated circuit from a mold of an aligned molding press.
In a preferred form of the invention, the molding presses and stations are arranged on a rotating index table, such that when a first molding press is aligned with the unloading station, a second molding press is aligned with the mold cleaning station, and a third molding press aligned with the loading and compound molding compound loading stations. Align all stations with respect to each other.
Preferably, the apparatus includes a first controller circuit mounted for movement with the molding presses, for independently controlling the opening and closing thereof. A second controller circuit may be provided to control functions of the stations, with the first and second controller circuits communicating by way of a rotating electrical connection. A similar rotating electrical connection may be provided to power the molding presses in the event that they are electrically operated. Alternatively, if the molding presses are hydraulic or pneumatic, then a rotatable hydraulic or pneumatic connection may be provided between a pressurised fluid source and hydraulic/pneumatic circuits of the molding presses and their counterparts.
In accordance with the present invention there is also provided a method for encapsulating integrated circuits, wherein at least one injection molding press and associated encapsulation mold is mounted for rotational movement into successive alignment with a plurality of respective stations arranged around the at least one molding press, comprising the steps of:
rotationally aligning the press with a first said station and thereat loading an integrated circuit die into the associated mold;
rotationally aligning the press with a second said station and thereat loading the press with an encapsulation material;
performing a transfer molding operation wherein said integrated circuit die is encapsulated with said material in said mold; and
rotationally aligning the press with a third said station and thereat unloading the encapsulated integrated circuit from the mold cleaning station.
Preferably a plurality of injection molding presses are used to repeatedly cycle through the method steps, such that when one of the steps is being performed on one press, another of the steps is being performed on another press.